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| 1 | +! GFORTRAN -O DSVD -STD=F2018 -WALL -PEDANTIC -O3 -FFAST-MATH -MARCH=NATIVE -FRECURSIVE DSVD.F90 -LBLAS -LARPACK |
| 2 | +! ORIGINAL CODE, HTTPS://GITHUB.COM/OPENCOLLAB/ARPACK-NG/BLOB/MASTER/EXAMPLES/SVD/DSVD.F |
| 3 | +! P110, HTTP://LI.MIT.EDU/ARCHIVE/ACTIVITIES/ARCHIVE/COURSEWORK/JU_LI/MITCOURSES/18.335/DOC/ARPACK/LEHOUCQ97.PDF |
| 4 | + |
| 5 | +MODULE SVD |
| 6 | + |
| 7 | + USE, INTRINSIC :: ISO_C_BINDING, ONLY: IK => C_INT, RK => C_DOUBLE |
| 8 | + IMPLICIT NONE |
| 9 | + |
| 10 | + PRIVATE |
| 11 | + |
| 12 | + REAL(RK), PUBLIC, PARAMETER :: SVD_LEVEL = 1.0E-9_RK ! SINGULAR VALUE THRESHOLD |
| 13 | + INTEGER, PUBLIC, PARAMETER :: SVD_ROW = 2_IK**12_IK ! MAX NUMBER OF ROWS |
| 14 | + INTEGER, PUBLIC, PARAMETER :: SVD_COL = 2_IK**12_IK ! MAX NUMBER OF ROWS |
| 15 | + INTEGER, PUBLIC, PARAMETER :: SVD_BASIS = 64_IK ! MAX NUMBER OF BASIS VECTORS IN THE IMPLICITLY RESTARTED ARNOLDI PROCESS, OPTIMAL VALUE (?) |
| 16 | + INTEGER, PUBLIC, PARAMETER :: SVD_LENGH = 16_IK ! LENGTH OF ARNOLDI FACTORIZATION |
| 17 | + INTEGER, PUBLIC, PARAMETER :: SVD_LOOP = 256_IK ! MAX NUMBER OF MAIN LOOP ITERAIONS |
| 18 | + |
| 19 | + |
| 20 | + PUBLIC :: SVD_TRUNCATED_ |
| 21 | + PUBLIC :: MATRIX_ |
| 22 | + |
| 23 | + EXTERNAL :: DSAUPD |
| 24 | + EXTERNAL :: DSEUPD |
| 25 | + EXTERNAL :: DGEMV |
| 26 | + EXTERNAL :: DGEMM |
| 27 | + |
| 28 | + CONTAINS |
| 29 | + |
| 30 | + SUBROUTINE SVD_TRUNCATED_(NR,NC,NS,MATRIX,LIST,RVEC,LVEC) |
| 31 | + INTEGER(IK), INTENT(IN) :: NR |
| 32 | + INTEGER(IK), INTENT(IN) :: NC |
| 33 | + INTEGER(IK), INTENT(IN) :: NS |
| 34 | + REAL(RK), DIMENSION(NR, NC), INTENT(IN) :: MATRIX |
| 35 | + REAL(RK), DIMENSION(NS), INTENT(OUT) :: LIST |
| 36 | + REAL(RK), DIMENSION(NC, NS), INTENT(OUT) :: RVEC |
| 37 | + REAL(RK), DIMENSION(NR, NS), INTENT(OUT) :: LVEC |
| 38 | + REAL(RK), DIMENSION(NS, NS) :: DIAG |
| 39 | + REAL(RK), DIMENSION(NC, NS) :: COPY |
| 40 | + INTEGER(IK) :: I |
| 41 | + REAL(RK), DIMENSION(SVD_COL, SVD_BASIS) :: V = 0.0_RK |
| 42 | + REAL(RK), DIMENSION(SVD_BASIS*(SVD_BASIS+8_IK)) :: WL |
| 43 | + REAL(RK), DIMENSION(3_IK*SVD_COL) :: WD |
| 44 | + REAL(RK), DIMENSION(SVD_BASIS,2_IK) :: S = 0.0_RK |
| 45 | + REAL(RK), DIMENSION(SVD_COL) :: ID |
| 46 | + REAL(RK), DIMENSION(SVD_ROW) :: AX |
| 47 | + INTEGER(IK) :: PAR(11_IK), PNT(11_IK) |
| 48 | + LOGICAL :: SELECT(SVD_BASIS) |
| 49 | + CHARACTER :: MAT*1 |
| 50 | + CHARACTER :: MODE*2 |
| 51 | + INTEGER(IK) :: IDO, NEV, NCV, WORK, INFO, IERR, NCONV |
| 52 | + REAL(RK) :: TOL, SIGMA |
| 53 | + ! ARPACK |
| 54 | + NEV = NS ! # OF SINGULAR VALUES TO COMPUTE, NEV < N |
| 55 | + NCV = MIN(SVD_LENGH, NC) ! LENGTH OF ARNOLDI FACTORIZATION |
| 56 | + MAT = 'I' ! OP = A^T.A |
| 57 | + MODE = 'LM' ! COMPUTE LARGEST (MAGNITUDE) SINGULAR VALUES, ALSO LA |
| 58 | + WORK = NCV*(NCV+8_IK) ! WORK ARRAY SIZE |
| 59 | + TOL = 0.0_RK ! TOLERANCE |
| 60 | + INFO = 0_IK ! INITIAL ERROR CODE |
| 61 | + IDO = 0_IK ! REVERSE COMMUNICATION PARAMETER |
| 62 | + PAR(1) = 1_IK ! SHIFT, 0/1 |
| 63 | + PAR(3) = SVD_LOOP ! MAX NUMBER OF ITERAIONS |
| 64 | + PAR(7) = 1_IK ! MODE |
| 65 | + ! MAIN LOOP |
| 66 | + MAIN : DO |
| 67 | + CALL DSAUPD(IDO,MAT,NC,MODE,NEV,TOL,ID,NCV,V,SVD_COL,PAR,PNT,WD,WL,WORK,INFO) |
| 68 | + IF (.NOT.(IDO .EQ. -1_IK .OR. IDO .EQ. 1_IK)) EXIT |
| 69 | + CALL DGEMV('N',NR,NC,1.0_RK,MATRIX,NR,WD(PNT(1)),1_IK,0.0_RK,AX,1_IK) |
| 70 | + CALL DGEMV('T',NR,NC,1.0_RK,MATRIX,NR,AX,1_IK,0.0_RK,WD(PNT(2)),1_IK) |
| 71 | + END DO MAIN |
| 72 | + ! RIGHT SINGULAR VERCTORS |
| 73 | + CALL DSEUPD (.TRUE.,'ALL',SELECT,S,V,SVD_COL,SIGMA,MAT,NC,MODE,NEV,TOL,ID,NCV,V,SVD_COL,PAR,PNT,WD,WL,WORK,IERR) |
| 74 | + ! SCALE, REVERSE AND SET SINGULAR VALUES |
| 75 | + NCONV = PAR(5) |
| 76 | + LIST = SQRT(ABS(S(NEV:1:-1,1))) |
| 77 | + ! TRIM |
| 78 | + WHERE (LIST < SVD_LEVEL) LIST = 0.0_RK |
| 79 | + ! REVERSE AND SET RIGHT VECTORS |
| 80 | + RVEC(:,1:NEV:1) = V(1:NC,NEV:1:-1) |
| 81 | + ! COMPUTE LEFT VECTOR, U = A.V.S^-1, DIRECT COMPUTATION |
| 82 | + DIAG = 0.0_RK |
| 83 | + DO I = 1 , NEV, 1 |
| 84 | + IF(LIST(I) > SVD_LEVEL) DIAG(I, I) = 1.0_RK/LIST(I) |
| 85 | + END DO |
| 86 | + CALL DGEMM('N','N',NC,NS,NS,1.0_RK,RVEC,NC,DIAG,NS,0.0_RK,COPY,NC) |
| 87 | + CALL DGEMM('N','N',NR,NS,NC,1.0_RK,MATRIX,NR,COPY,NC,0.0_RK,LVEC,NR) |
| 88 | + END SUBROUTINE SVD_TRUNCATED_ |
| 89 | + |
| 90 | + SUBROUTINE MATRIX_(LENGTH, SEQUENCE, MATRIX) |
| 91 | + INTEGER(IK), INTENT(IN) :: LENGTH |
| 92 | + REAL(RK), DIMENSION(LENGTH), INTENT(IN) :: SEQUENCE |
| 93 | + REAL(RK), DIMENSION(LENGTH/2_IK+1_IK, LENGTH/2_IK), INTENT(OUT) :: MATRIX |
| 94 | + INTEGER(IK) :: I |
| 95 | + DO I = 1_IK, LENGTH/2_IK+1_IK, 1_IK |
| 96 | + MATRIX(I, :) = SEQUENCE(I:I-1_IK+LENGTH/2_IK) |
| 97 | + END DO |
| 98 | + END SUBROUTINE MATRIX_ |
| 99 | + |
| 100 | +END MODULE SVD |
| 101 | + |
| 102 | +PROGRAM DSVD |
| 103 | + USE, INTRINSIC :: ISO_C_BINDING, ONLY: IK => C_INT, RK => C_DOUBLE |
| 104 | + USE SVD |
| 105 | + IMPLICIT NONE |
| 106 | + BLOCK |
| 107 | + INTEGER(IK), PARAMETER :: LENGTH = 2_IK**4 |
| 108 | + INTEGER(IK), PARAMETER :: NR = LENGTH/2_IK + 1_IK |
| 109 | + INTEGER(IK), PARAMETER :: NC = LENGTH/2_IK |
| 110 | + INTEGER(IK), PARAMETER :: NS = 3_IK |
| 111 | + |
| 112 | + REAL(RK) :: SEQUENCE(LENGTH) |
| 113 | + REAL(RK) :: MATRIX(NR,NC) |
| 114 | + REAL(RK) :: SVD_LIST(NS) |
| 115 | + REAL(RK) :: DIAG(NS,NS) |
| 116 | + REAL(RK) :: RVEC(NC,NS) |
| 117 | + REAL(RK) :: LVEC(NR,NS) |
| 118 | + |
| 119 | + INTEGER :: I |
| 120 | + |
| 121 | + SEQUENCE = REAL([(I, I = 1, LENGTH, 1)], RK) |
| 122 | + CALL MATRIX_(LENGTH, SEQUENCE, MATRIX) |
| 123 | + |
| 124 | + WRITE(*, *) "INPUT MATRIX" |
| 125 | + WRITE(*, *) SIZE(MATRIX,1) |
| 126 | + WRITE(*, *) SIZE(MATRIX,2) |
| 127 | + DO I=1,NR,1 |
| 128 | + WRITE(*, *) INT(MATRIX(I,:)) |
| 129 | + END DO |
| 130 | + WRITE(*, *) |
| 131 | + |
| 132 | + CALL SVD_TRUNCATED_(NR, NC, NS, MATRIX, SVD_LIST, RVEC, LVEC) |
| 133 | + DIAG = 0.0_RK |
| 134 | + WRITE(*, *) "SINGULAR VALUES" |
| 135 | + DO I = 1, NS, 1 |
| 136 | + DIAG(I, I) = SVD_LIST(I) |
| 137 | + WRITE(*, *) DIAG(I, :) |
| 138 | + END DO |
| 139 | + WRITE(*, *) |
| 140 | + |
| 141 | + WRITE(*, *) "RIGHT VECTORS" |
| 142 | + DO I = 1, NC, 1 |
| 143 | + WRITE(*, *) RVEC(I,:) |
| 144 | + END DO |
| 145 | + WRITE(*, *) |
| 146 | + |
| 147 | + WRITE(*, *) "LEFT VECTORS" |
| 148 | + DO I = 1, NR, 1 |
| 149 | + WRITE(*, *) LVEC(I, :) |
| 150 | + END DO |
| 151 | + WRITE(*, *) |
| 152 | + |
| 153 | + MATRIX = MATMUL(LVEC, MATMUL(DIAG, TRANSPOSE(RVEC))) |
| 154 | + WRITE(*, *) "U.S.V^T" |
| 155 | + DO I=1, NR, 1 |
| 156 | + WRITE(*, *) CEILING(MATRIX(I, :)) |
| 157 | + END DO |
| 158 | + WRITE(*, *) |
| 159 | + |
| 160 | + END BLOCK |
| 161 | +END PROGRAM DSVD |
| 162 | + |
| 163 | + |
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